Field of the Invention
The present invention relates to a multilayered ceramic capacitor and a board for mounting the same.
Description of the Related Art
In general, multilayered ceramic capacitors, multilayered chip electronic components, are chip shaped condensers mounted on printed circuit boards of various electronic products such as display devices, for example, liquid crystal displays (LCDs), plasma display panels (PDPs), and the like, computers, smart phones, mobile phones, and the like, serving to charge or discharge electricity.
Since this multilayered ceramic capacitor (MLCC) has advantages such as a small size, high capacitance, ease of mounting, or the like, the multilayered ceramic capacitor may be used as a component of various electronic devices.
The multilayered ceramic capacitor may have a structure in which a plurality of dielectric layers and internal electrodes having opposite polarities while having the dielectric layer interposed therebetween are alternately stacked.
Since the dielectric layers have piezoelectric and electrostrictive properties, when direct current (DC) or alternating current (AC) voltage is applied to the multilayered ceramic capacitor, a piezoelectric phenomenon is generated between the internal electrodes, thereby causing vibrations.
These vibrations may be transferred to a printed circuit board on which the multilayered ceramic capacitor is mounted through a solder of the multilayered ceramic capacitor, such that the entire printed circuit board may become an acoustic reflective surface generating a vibration sound, known as noise.
The vibration sound may have a frequency corresponding to an audio frequency in a region of 20 to 20000 Hz, making a person uncomfortable. The vibration sound making the person uncomfortable as described above is known as acoustic noise.
In order to reduce acoustic noise, research into a product having a form in which a thickness of a lower cover layer of the multilayered ceramic capacitor is increased has been conducted.
In addition, when the multilayered ceramic capacitor having the increased thickness of the lower cover layer is mounted on the printed circuit board, the thick lower cover layer may be positioned in a lowermost position so as to be advantageous in decreasing acoustic noise, such that the multilayered ceramic capacitor may be mounted in a horizontal mounting scheme.
Meanwhile, in the case of a product having a form in which the thickness of the lower cover layer of the multilayered ceramic capacitor is increased in order to reduce acoustic noise, a crack defect or a delamination defect may be generated in a sintering process due to a difference in density between a region in which the internal electrodes are formed and a region in which the internal electrodes are not formed.